3-10
1. The CPU module floating decimal point data can be monitored using the
monitoring function of a peripheral device.
2. When floating-point data is used to express 0, all data in the following range are
turned to 0.
(a) Single-precision floating-point data: b0 to b31
(b) Double-precision floating-point data: b0 to b63
3. The setting range of floating decimal point data is as follows. *
1
(a) Single-precision floating-point data
2
128
< Device data 2
-126
, 0, 2
-126
Device data < 2
128
(b) Double-precision floating-point data
2
1024
< Device data 2
-1022
,0,2
-1022
Device data < 2
1024
4. Do not specify 0 in floating-point data (when only the most significant bit of
the floating-point real number is 1). (An operation error will occur if
floating-point operation is performed with 0.) The CPU module that performs
the internal operation of floating-point operation with double precision does not
result in operation error since it performs floating-point operation after
converting 0 into 0 in the CPU module when 0 is specified. The CPU
module that performs the internal operation of floating-point operation with
single precision results in operation error since it gives priority to the processing
speed and uses 0 in floating-point operation without conversion when 0 is
specified.
(a) The following CPU modules will not result in operation error when 0 is
specified.
• High Performance model QCPU where internal operation is set to
double precision *
2
(The internal operation of floating-point operation defaults to double
precision.)
(b) The following CPU modules will result in operation error when -0 is
specified.
• Basic model QCPU *
3
• High Performance model QCPU where internal operation is set to single
precision *
2
• Process CPU
• Redundant CPU
• Universal model QCPU
*1: For operations when a real number is out of range and operations when an invalid value is input, refer to the
QnUCPU User's Manual (Function Explanation, Program Fundamentals) or Qn(H)/QnPH/QnPRHCPU
User's Manual (Function Explanation, Program Fundamentals).
*2: Switch between single precision and double precision of the internal operation of floating-point operation in
the PLC system of the PLC parameter dialog box. For the single precision and double precision of floating-
point operation, refer to the QnUCPU User's Manual (Function Explanation, Program Fundamentals) or
Qn(H)/QnPH/QnPRHCPU User's Manual (Function Explanation, Program Fundamentals).
*3: The Basic model QCPU can perform floating-point operation if its first five digits of serial No. are "04122 or
later".